RFC: WPRoll Plugin

Idea: a website service / plugin combo that will allow the user to register their WP-powered site. Then the plugin would then allow them to display a list of other WP sites. Kinda like how BlogRoll works, only you wouldn’t need to add the sites yourself, just yours, then add in the plugin.

Ultimately it would work like this:
You’d sign up at the site. Download the plugin, activate it, set some options, add the template tag to your template file(s). And viola! Done. You would then have a list of links to other WP sites.

Good idea? Bad idea? Am I wasting my time & energies? Is there anyone interested in helping out?